Induction furnace



Fatented Oct. 25, 1927...

UNITED STATES WILLIAM HosxINs, orcHIoAGo, ILLINOIS.

INDUCTION FURNACE.

Application filed .Tune 3,

rlhe present invention relates to improvements in electric induction furnaces and particularly to means effecting, among other results, a stirring action and movement of the material4 along the heating receptacle; It will be fully understood from the tol` lowingr description, illustrated by the accompanying drawings, in which 1- Figure l is a diagrammatic vertical sectional View of an improved furnace showing one embodiment of my invention, the section being taken as indicated at line 1 -1 of Fig. 2; Fig. 2.is a plan sectional view taken as indicated at line 2-2 on Fig. l; Fig. 3 is a vertical sectional view, similar l to Fig. 1, showing, however, only the right half of the furnace and indicating by arrows the direction of rotation of the molten metal in the heating receptacle and also showing a spiral channel in the bottoni of the heating receptacle; Fig. el vis a vertical sectional view of the heating receptacle showing a spiral projection or fin in the bottom thereof; and Fig. 5 is an enlarged plan sectional view of the bottom of the heating receptacle showing the spiral projections or channels therein.

Referring more particularly to Figs. 1 and 2. the numeral l represents a ring-like trough communicating on one side of the furnace with an enlarged chamber 2. The

trough 'l and chamber 2 are" supported 1n a furnace setting 3 which may be constructed of magnesite or any suitable refractory and non-conducting material. Numeral 4 represents a tran=former core of the ligure 8 type, the central leg 4 of which passes through the ring-like trough l and the side legs 43 of which are just outside the urnacg walls or setting 3. Numeral 5 represents .a suitably insulated primary coil Wound around the central leg la of the transformer core 4. A cooling space 6 is provided toprotectthe primary coil 5 from the heat generated within the trough 1. If desired,l however, watercooled pi es or other cooling means may he employe around the coils. I havenshown the chamber 2 provided with an opening 3 in the Walls oi' the furnace setting 3 through which material ma be supplied to and withdrawn from the c amber 2. Hoi/Voyer, :for the purposes of my invention, the chamber 2 and trough l may be either closed or opened. y

While I prefer to use a transformer core of the ligure 8 type, an ordinarv rectangular 1927. Serial No. 196,232.

transformer core or any other suitable kind of core may, if desired,`be employed. Also, l

While I have shown a trough circular in cross section and ring-like in horizontal section, it is clearly within the spirit of my invention to use troughs of other shapes in which a rotation of the liquid metal in a vertical plane, as hereinafter described, will take place.

In theoperation of certain electric furnaces, 1t is desirable to stir a bath of Huid metal while it is maintained at a very high degree of temperature. Also it is desirable to heat the metal primarily in a restricted chamber or trough of small cross section and to supply the metal, when sufficiently heated, to a reservoir or chamber of larger cross section. These and other advantages I secure as follows. It is known that in an induction furnace, in which the metal bath chamber is not straight but shaped to form a closed circuit, that a rotation or circulation of the metal takes place in a. vertical plaine. This is illustrated in Fig. 3' in which airows indicate the direction in which thlilquid metal rotates with relation to the pniinary coil 5. I propose to convert the vertlca movement of the molten material into aiforward or substantially horizontal motement by placing fixed inclined obstructions in the 'trough or chamber or in both trough and chamber. Preferably these Vobstructions are spiral in Vvshape and may be in the form of grooves or chanels 7, 'as shown in Fig. 3, or projections 7", as shown in Fig. 4. While I have illustratedin Figs. 3, 4 and 5 a referred type of trough in which the bottom alone is ried or provided with grooves 7a or projections 7b, it will be understood that the entire trough may, ifV desired, be rifled or rovided with inclined obstructions.

n the operation of the a paratus, I prefer to employ a single-phase a ternating current. As the fluid metal is set in rotation or circulation in a vertical lane, the inclined obstructions itch the llquid forward in a substantially, orizontal plane along the Walls of the trough. In this manner the metal, which is heated4 to a high temperature in a channel of narrow cross section, Ais passed into the reservoir or chamberof large cross section 2. Also', the whirling movement given the liquid by the inclined obstructions ve e'ectively stirs the metal.

t is not intended that the details of ap- 1. An induction furnace comprising a Acurved rifled trough supported Within a fui'- nace setting, conducting material in Asaid trough, means for inducing an electric current in said material whereby a rotation of said material is produced, and means forsupplying material to and withdrawing material from said trough.

2. An electric induction furnace comprising a circular trough, a chaniberof greater cross-section communicating with said trough, material in said trough and chamber to be heated, means for inducing an electric current iii said material whereby a rotation of the material is secured, and inclined obstructions in said trough positioned obliquel to the line directed toward the center ot the trough and serving to 'advance the inalterial along the trough.

3. In a device of the character set forth, a refractory container in the form of a ring,

`means' for inducing electric currents in material Within said container, said means cornprising inducing a variable magnetic field in a plane substantially at right angles to the plane of the container, and causing a rotation of said material, and means within the container positioned obliquely With respect tothe line directed toward the center of the container for advancing the material around the container.

4. In a device 'of the character set forth,

a trough supported within a furnace setting ing a chamber and a trough communicating' vat its two ends with the chamber and ornr -ing therewith a complete circuit, means for inducing an electric current in the material `within thel trough and chamber, whereby a substantially rot-ary movement of the inaterial is e'ected, and inclined obstructions in the trough serving to, advance material .to and from the. chamber.

l WILLIAM HOSKNS. 

